© C.O. Evans
 Two distinctively different philosophical issues have usually been discussed under the heading of personal identity. One concerns itself with our knowledge of the identity of persons other than ourselves, and the other concerns itself with self-awareness. Although the expressions 'personal identity' and 'self-identity' have commonly been used interchangeably by philosophers, I would like to suggest that there is point in reserving the first expression to describe the problem of the identity of persons, and the second to describe the problem of self-awareness.
Many philosophers would not agree that there are two different problems involved. In this introduction I try to make out a case that there are. If there were a difference between the problem of personal identity and that of self-identity, it would follow that the two questions, (a) What is a person? and (b) What is the self? are different questions and not merely different formulations of the same question.
It might be thought that what makes the two questions different is not the use of the word 'person' in (a) and the word 'self' in (b), but the use of the indefinite article in (a) and the definite article in (b). Were this the case it would be possible to make the two questions identical by the simple expedient of using the indefinite article in both. With this I would concur. But the significant point is that we cannot use the definite article in both cases. The sentence 'What is the person' is ungrammatical.
It will emerge in due course that there are more powerful reasons for refraining from posing the problem of self-awareness in terms of the concept of a person. At this point, however, all that needs to be pointed out is that the nature of self-awareness has been a preoccupation of philosophers and their curiosity about self-awareness is not satisfied either by knowledge of the identity of other persons or by knowledge of the criteria on which such knowledge is based. It is less misleading, therefore, to phrase the problem 'Of what are we aware in self-awareness?' in terms of the question, 'What is the self?', than it is to phrase it in terms of a
question about persons. Furthermore the question 'What is a person?' leaves it open whether or not the reader himself is included within the class of persons. This is not left open with the question 'What is the self'. For that question is one which the reader must address to himself if he is to understand it. The question pragmatically implies token-reflexivity -it becomes for each reader the question, 'In what does my identity as a self consist?'
Many of the best philosophers writing today on personal identity would strongly resist an attempt such as this to insert a wedge between the concepts 'person' and 'self'. Indeed they would prefer to avoid the word 'self' altogether, and discuss the problem exclusively in terms of the word 'person'. Their approach is based on the contention that there is no distinction between identity in one's own case and identity in the case of others, and hence that an understanding of the identity of persons in general is eo ipso an understanding of one's own identity.
It needs to be pointed out, however, that this contention could not even be stated unless each of us knew that he was a member of the class of persons. This would give rise to the question of what entitles us to make this knowledge claim. It would be tempting to say that it is analytically true that persons and persons only are able to raise questions about their own identities. The trouble with this move is that it makes it impossible to equate persons with human beings, because it must be left at least a logical possibility for a being other than a human being to raise the question of self-identity. But I shall let that pass.
The approach just alluded to - let me call it the persons-approach - is part of a programme of deliberate reversal of the traditional approach to epistemology. The tradition emanating from Descartes was to begin an epistemological enquiry with one's own case, and, from that starting point, arrive by inference at knowledge claims about things apart from oneself. However, philosophers have since come to believe that many of the insoluble problems of knowledge can be traced back to the premiss that one must start with one's own case. From their point of view, therefore, the suggestion that the problem of one's own identity is distinct from the problem of the identity of other persons appears to be a regression to the unfortunate method of starting with one's own case.
It is fear of such regression, I believe, that has made philosophers wary of references to the self, and has caused them to see the
problem of personal identity as primarily a problem of the identity of other persons, and only derivatively a problem of self-identity. According to the persons-approach we learn all there is to know about self-identity by understanding in what the identity of other persons consists.
The persons-approach has been very successful, and the philosophy of personal identity is one area in which definite progress has been made. Philosophers would therefore have good cause to be suspicious of the apparent re-introduction of a distinction which threatens this hard-won progress. I hope to show that the distinction I have in mind poses no such threat, and that the recognition of a separate problem of self-identity leaves intact the progress made in our understanding of personal identity. I shall in fact be arguing for an even stronger claim than this: namely, that the two problems are complementary and that only when both problems have been solved will we have an adequate understanding of our own identities.
If I am right about this, then a solution to the one problem must not contradict the solution to the other problem. That is to say, an answer to the question 'What is the self' must not contradict the answer to the question 'What is a person?' Furthermore, an answer to the first question must not be thought to supply the answer to the second question and vice versa. I wish to stress this because it rules out any attempt to arrive at a theory of personal identity by reverting to the traditional method of starting with one's own case. Once it is realized that the distinction between person and self has no such implication, nothing is lost in at least allowing the distinction to go forward, and for the sake of argument.
The problems of personal identity and self-identity can only be logically separate from each other if the identity sought is different in the two cases. I shall argue that this is indeed the case.
The concept of identity is a difficult one to understand at the best of times, and this difficulty is added to in discussions of personal identity because identity is apt to be confused with identification. In answer to the question 'Which is it?' we provide what I shall call referential identification. In answer to the question 'What is it?' we provide - what I shall call sortal identification. (I shall not be concerned at the moment with a third type of identification in which we answer the question 'Whose is it?' by providing what may be called possessive identification.) It is clearly the case that successful referential identification will give us some broad
knowledge of the sort of object identified. It can reveal whether the object in question is a physical object, an animal, or something less solid like thunder and lightning. The relevance of this point is brought out by Shoemaker who notes:
To say what sort of criteria we use in making judgments about the identity of objects of a certain kind is to say something, often a great deal, about the nature (essence, concept) of that sort of object. Thus it is that the problem of personal identity is a problem about the nature of persons. 1
It must nevertheless be insisted that referential identification has a different logical function from sortal identification.